I got anywhere between 19.5-21.5 from my '91 4.0 5spd. That had 235/75R15 tires and 3.55 gears from an auto, speedometer was corrected so mileage was accurate. I just got 18.5 from my '98 4.0 5spd, that included a good bit of idle time as well as the occasional beating on it. That still has the factory 3.07 gears. I remember picking up about 1mpg when i swapped gears on my '91, probably because i dont do much highway

 

When my old 97 (ax15) was stock I would average about 350 a tank. Once in a while I would hit the 400 miles per tank. The 400 would be highway miles though.

 

You guys always compare MpGs but really every jeep is different. From tires to amount of red light to what line on the gas gauge we compare from. Not worth waiting time. All highway i get 350-400. I get 200-210 mixed driving with alot of traffic

 

Well, I'm getting 260 80% stop and go city driving, averaging 14.5.

When I was out in the boondocks I could get up to the high 19 driving like there was an egg under the loud pedal.

 

I just installed some 31-10.50's so let's see what happens now lol.

 

On 235/75/15 I get 13-15 on my stock 91 with 207,000. It is really cold. I once got 22 with a strong wind at my back. In October I got around 18-19 mostly long back roads doing about 55-60. My moms 01 grand gets about the same mileage so I'm happy.

 

well then my sending unit is all crapped out then... because when my gas light comes on.. i put 14 gallons in and it topped it back off... i thought i had a 15 gallon tank... guess its 20, and my sending unit is off...

 

That sounds about right my 98 was at 23/27 with 215/75/15 now I'm at about 20/24 with 225/75/16 also don't have a 4wd either.
My 88 gets around 260 with 3gallons left in the tank the girl 88 pushes around 320 to empty which I can't figure out why 254k motor. But my sister only gets like 225 in her 95 all three are 4wd auto, all have 20 gal tanks too.

 

33's, geared at 4:56, and correct speedo gear. I average 260 miles per tank around town , all stop and go traffic. Long trips with the cruise control at 65 mph I average 330 miles per tank. Fill ups always fall between 15 and 16 gallons. 16-17 mpg in town and 20-22 mpg hwy (based off 3 recent trips to CO). Better than I figured on, when I built it. I don't drive it hard or overly soft. Just somewhere comfortably in the middle.

 

I have an 85 2.5l auto which was getting about 17-19mp(one backroad trip actually got me 20+) until I fixed the hole in the tubing running from the PCV to the bottom of the carb, now it gets 15mpg or less. Strange, I though a vacuum leak would hurt mileage not improve it lol.

I put 19.8 gallons in the tank the other day and the low fuel light still had not come on. Guess I can't trust that either. Averaging 300 miles or less right now once the gauge hits the red zone.

 

Going by the jeeps trip (I know its not completely accurate) I get about 120 miles per tank. 33s, 3.55 gears, evap leak, both O2 sensors shot, and slight exhaust manifold leak. Only my DD when it snows or I don't feel like driving my truck (which is often)

 

****, with 3.08 or whatever stock gears, my XJ on 33's can BARELY nudge out 240 miles before the low fuel light clicks on. Works out to around 14-15mpg which is straight terrible.

 

You guys with stock gears and larger tires do you have the correct speedo gear? If not then are you calculating your miles out correct?

 

This, so many people over look this. It takes 5 minutes to swap the gear yet nobody ever thinks about it

 

Since I put 235s on mine, and it originally had 208s on it from the factory, I was going to change out my gear, but I checked it last week with a GPS and the darn thing is dead on speed wise. Should have been off about 4mph at 60. It has 3.73 gears so maybe it didn't make that much difference with the tires.